This document specifies the characteristics of the fitness for purpose of oriented unplasticized poly(vinyl chloride) (PVC-O) solid wall piping intended to be used underground or above-ground where protected from direct sunlight, for water supply, buried drainage, sewerage, treated wastewater and irrigation under pressure. It also specifies the test parameters for the test methods referred to in this document. This document is not intended for on-site testing of pipe systems. In conjunction with ISO 16422-1, ISO 16422-2, ISO/TS 16422-3 and ISO 1452-3, this document is applicable to PVC-O pipes and PVC-O fittings, as well as to their joints and to joints with components of other plastics and non-plastics materials intended to be used for the following: a)       water mains and services lines; b)       conveyance of water for both outside and inside buildings; c)        drainage, sewerage and treated wastewater under pressure; d)       irrigation under pressure. This document is applicable to piping systems intended for the supply of water under pressure up to and including 25 °C (cold water), intended for human consumption and for general purposes as well as for wastewater under pressure. This document is also applicable to components for the conveyance of water and wastewater up to and including 45 °C. For temperatures between 25 °C and 45 °C, see ISO 16422-2:2023, Figure C.1. The piping system according to this document is intended for the conveyance of cold water up to pressures of 25 bar[1] and especially in those applications where special performance requirements are needed, such as impact loads and pressure fluctuations, up to pressure of 25 bar. [1]  1 bar= 0,1 MPa = 105 Pa; 1 MPa= 1 N/mm2